Cryptography Questions
Part of the Cybersecurity Roadmap
In short
Crypto questions check whether you truly understand the basics or just memorised names. Clear differences and a real example beat fancy maths every time.
'Explain the difference between symmetric and asymmetric encryption' or 'how does TLS work?' — testing Phase 4 and Phase 12's cryptography fundamentals in plain, clear language.
Think of it like this
The practical exam viva
In a lab viva, the examiner does not just ask "what is a resistor?". They ask why you chose it and what happens if it is wrong. Crypto interviews are vivas too: know what each tool does, when to use it and what breaks if misused.
Watch it happen
Question families to prepare
1/5Symmetric uses one shared key and is fast; asymmetric uses a key pair and solves key sharing.
The big ideas
What you need to know
Define, then example
Give a one line definition, then a real use: "AES encrypts disk data; RSA or ECDHE helps set up the key."
Talk trade offs
Speed vs key sharing, integrity vs secrecy. Trade offs show you understand, not just recall.
Know what is broken
MD5, SHA-1, DES and SSL are outdated. Say why and what replaces them.
It is fine to say I would check
For exact key sizes or new standards, saying "I would confirm against current NIST guidance" is honest and professional.
See it in code
A tiny example
1echo -n "secret" | base64 # c2VjcmV0 (encoding: anyone reverses it)2echo -n "secret" | sha256sum # one way fingerprint, no key3openssl enc -aes-256-cbc -pbkdf2 -in note.txt -out note.enc # needs a passwordThree lines that answer a classic interview question: encoding, hashing and encryption are different things with different guarantees.
Save yourself the pain
Common mistakes
Oops
Saying passwords should be encrypted in the database.
Do this instead
Passwords should be hashed with a slow, salted password hash. Encryption implies someone can decrypt them.
Oops
Calling Base64 a type of encryption.
Do this instead
Base64 is just encoding for safe transport. It provides zero secrecy.
Your mission
Answer five crypto questions aloud
Quick check
An app stores user passwords using AES encryption with a key in the config. What is the main problem?
Go deeper
- 1Review Phases 4 and 12 and practice explaining each concept without jargon.
- 2Prepare to diagram a TLS handshake from memory.
- 3Practice explaining why hashing (not encryption) is the correct choice for password storage.
More technical fundamentals at this stop
Networking & Protocol Questions
OS & Linux Questions
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